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Δύο ευαίσθητες περιοχές στην ερημοποίηση, αντιπροσωπευτικές του Μεσογειακού περιβάλλοντος με σημαντικές για τις Ελληνικές συνθήκες χρήσεις γης, χρησιμοποιήθηκαν ως πεδία έρευνας της παρούσας διατριβής. Οι περιοχές αυτές που χαρακτηρίζονται από διαφορετικά εδαφοκλιματικά χαρακτηριστικά και εντάσεις χρήσεων γης καταλαμβάνουν κατά προσέγγιση έκταση ενός εκατομμυρίου στρεμμάτων και βρίσκονται στους νομούς Χανίων και Ηρακλείου της νήσου Κρήτης. Σημαντικό τμήμα των περιοχών αυτών χαρτογραφήθηκε και μελετήθηκε ως προς τα εδάφη, την αναπτυσσόμενη βλάστηση και το κλίμα ενώ παράλληλα με τη χρήση ερωτηματολογίων και τη συμμετοχή των τοπικών παραγωγών καταγράφτηκαν σε επίπεδο αγροκτήματος ένα σύνολο από 70 βιοφυσικούς και κοινωνικοοικονομικούς δείκτες σε δείγμα 171 αγροκτημάτων (τοπικό επίπεδο). Στο πλαίσιο της παρούσας διατριβής και της υλοποίησης του ερευνητικού προγράμματος DESIRE παραχωρήθηκε η χρήση των δεδομένων 1785 αντίστοιχων ερωτηματολογίων από 18 περιοχές έρευνας παγκόσμιας κλίμακας (περιφερειακό επίπεδο). Σε δύο από τις κύριες χρήσεις γης (ελαιώνας και βοσκότοπος) των περιοχών έρευνας της Κρήτης εγκαταστάθηκαν για τρία χρόνια (2008-2011) αυτόματοι σταθμοί καταγραφής εδαφικών και μετεωρολογικών δεδομένων με σκοπό την ποσοτική εκτίμηση της επιφανειακής υδατικής διάβρωσης και της απώλειας εδαφικού ιζήματος σε διάφορες παραδοσιακές καλλιεργητικές πρακτικές και εντάσεις χρήσης.Τα δύο προαναφερόμενα δείγματα των ερωτηματολογίων (περιφερειακής και τοπικής κλίμακας) αναλύθηκαν στατιστικά προκειμένου να εξαχθούν οι πιο σημαντικοί δείκτες που επηρεάζουν τον κίνδυνο ερημοποίησης των γαιών ανά διεργασία υποβάθμισης και κυρίως εξαιτίας της επιφανειακής υδατικής διάβρωσης σε περιφερειακό και τοπικό επίπεδο. Ειδικά σε τοπικό επίπεδο και συγκεκριμένα στα δεδομένα των ερωτηματολογίων της Κρήτης εφαρμόστηκε μια καινοτόμος στρατηγική στη στατιστική ανάλυση με την εκτέλεση διερευνητικών μη παραμετρικών πολυμεταβλητών στατιστικών ελέγχων και τη χρήση της εκτιμώμενης στον αγρό ιδιότητας του βαθμού διάβρωσης. Χρησιμοποιώντας τα αποτελέσματα της πειραματικής καταγραφής της επιφανειακής υδατικής διάβρωσης και της απώλειας εδαφικού ιζήματος για τρία χρόνια αξιολογήθηκε η επίδραση διαφορετικών καλλιεργητικών πρακτικών και διαχειρίσεων των γαιών στην ερημοποίηση λόγω διάβρωσης σε δύο αντιπροσωπευτικές χρήσεις γης του Μεσογειακού περιβάλλοντος. Επίσης με τα δεδομένα των τριετών μετρήσεων πραγματοποιήθηκε πειραματική επιβεβαίωση του εκτιμώμενου με χρήση της μεθοδολογίας P.E.S.E.R.A. (Pan–European Soil Erosion Risk Assessment) κινδύνου διάβρωσης σε επίπεδο αγροτεμαχίου (τοπική κλίμακα) δεδομένου ότι το μοντέλο είχε ήδη προσαρμοσθεί στις μεσογειακές και ειδικά στις ελληνικές συνθήκες από παλαιότερες εργασίες. Ολοκληρώνοντας τις προσεγγίσεις της μελέτης του φαινομένου της ερημοποίησης των γαιών πραγματοποιήθηκε η εφαρμογή των μεθοδολογιών P.E.S.E.R.A. και E.S.A. (Environmentally Sensitive Areas) σε περιφερειακό επίπεδο για την περιοχή μελέτης του νομού Χανίων και στις συνθήκες 28 διαφορετικών σεναρίων καλλιεργητικών πρακτικών και διαχείρισης των γαιών με στόχο τη συγκριτική ανάλυση των σεναρίων διαχείρισης και καλλιέργειας των γαιών ως προς τον κίνδυνο διάβρωσης και ερημοποίησης σε επίπεδο νομού. Το λογικό πλαίσιο που αναπτύχθηκε στην παρούσα διατριβή σε συνδυασμό με την εμπειρική ανάλυση που βασίστηκε σε περιγραφική, διερευνητική, επαγωγική και πολυπαραγοντική στατιστική επεξεργασία, επιτρέπει την εκτίμηση του κινδύνου ερημοποίησης των γαιών, με τη χρήση περιορισμένου αριθμού δεικτών, σε περιοχές διαφορετικής περιβαλλοντικής ευαισθησίας αξιοποιώντας δεδομένα περιφερειακού ή τοπικού επιπέδου. Καθώς επιτόπιες ποσοτικές μετρήσεις της επιφανειακής υδατικής διάβρωσης και της απώλειας εδαφικού ιζήματος είναι σπάνιες η αξία της χρήσης των πειραματικών δεδομένων για την αξιολόγηση της συνεισφοράς συγκεκριμένων καλλιεργητικών πρακτικών στην αειφορία του περιβάλλοντος σε επίπεδο αγροκτήματος είναι ανεκτίμητη. Η πειραματική αξιολόγηση των καλλιεργητικών πρακτικών είναι δυνατόν να ανατρέψει λανθασμένες αντιλήψεις για την καλλιέργεια των γαιών και την προστασία του περιβάλλοντος αποτρέποντας περαιτέρω υποβαθμίσεις. Επιπρόσθετα με τη χρήση αξιόπιστων επιστημονικών μοντέλων προσομοίωσης της επιφανειακής υδατικής διάβρωσης (P.E.S.E.R.A.) για την εκτίμηση του κινδύνου διάβρωσης και εκτίμησης του κινδύνου ερημοποίησης (E.S.A.) καθίσταται εφικτή η εξακρίβωση της επίδρασης των παραδοσιακών ή καινοτόμων πρακτικών στην αειφορία των φυσικών πόρων σε περιφερειακή κλίμακα. Τέτοιου είδους προσομοιώσεις είναι δυνατόν να θεωρηθούν ως πολύτιμα «εργαλεία» για τους έχοντες την ευθύνη λήψης πολιτικών αποφάσεων που αφορούν τη γεωργία και το περιβάλλον.

The impact of simulated future climate change on land degradation was assessed in three representative study sites of Thessaly, Greece, one of the country’s most important agronomic zones. Two possible scenarios were used for estimation of future climatic conditions, which were based on greenhouse gas emissions (RCP4.5 and RCP8.5). Three time periods were selected: the reference past period 1981–2000 for comparison, and the future periods 2041–2060 and 2081–2100. Based on soil characteristics, past and future climate conditions, type of land uses, and land management prevailing in the study area, the Environmentally Sensitive to desertification Areas (ESAs) were assessed for each period using the MEDALUS-ESAI index. Soil losses derived by water and tillage erosion were also assessed for the future periods using existing empirical equations. Furthermore, primary soil salinization risk was assessed using an algorithm of individual indicators related to the natural environment or socio-economic characteristics. The obtained data by both climatic scenarios predicted increases in mean maximum and mean minimum air temperature. Concerning annual precipitation, reductions are generally expected for the three study sites. Desertification risk in the future is expected to increase in comparison to the reference period. Soil losses are estimated to be more important in sloping areas, due especially to tillage erosion in at least one study site. Primary salinization risk is expected to be higher in one study site and in soils under poorly drainage conditions.

The management of agroecosystems affects biodiversity at all levels from genetic to food-web complexity. Low-input farming systems support higher levels of genetic, species and habitat diversity than high-input, industrial ones. In Greece, as in other Mediterranean countries, the role of traditional farming practices has been underlined in studies concerning conservation in agricultural landscapes. With this study, we aim to provide evidence for the potential of semi-extensive farming for biodiversity conservation at landscape-scale, focusing on Lemnos, a medium-sized island in the North Aegean. Evidence was gathered by species- and community-level local-scale surveys on various trophic levels (vascular plants, arthropods, birds). The surveys took place in 2018 and 2019 in 25 sampling areas comprising 106 plots of 100 m2 (vascular plants, arthropods) and 57 points where bird species were recorded. The plots were classified into three landscape types: mosaic agriculture, mixed rangelands and uniform rangelands. The releves of Lemnos farmlands were assigned to plant communities of 18 phytosociological alliances, grouped into 12 classes. The most abundant arthropods were Coleoptera, Chilopoda, and Hymenoptera, followed by Opiliones and Isopoda, while 133 different bird species were recorded in total, including the recording for the first time on the island of five species. Farming on Lemnos is rather extensive compared to most agricultural landscapes of Europe. Our approach has demonstrated that, given the geographic characteristics of the area, the measured data reveal very high biodiversity. Our explorative findings suggest that moderate seasonal grazing, the mixed habitat mosaic with ecotones, fallow and stubble fields at the landscape scale, and the small size of fields, the kinds of crop, and farm-scale crop diversification, like mixed cultivation and crop rotation, are key practices supporting this diversity. These explorative findings are considered as a first step providing the baseline for future assessments. A wider effort, for systematic evaluation of the impacts of farming practices to biodiversity, is required, as part of a subsidized agri-environmental scheme and/or through a market-oriented product certification system for the area.

The effects of four main practices tillage versus no-tillage, and intensive grazing versus extensive grazing, applied in characteristic agricultural and grazing lands of Crete Island were evaluated in situ using nine soil quality indicators. The following nine representative indicators of soil quality were evaluated using the rapid visual assessment methodology adopted at European level in the context of the EU research project iSQAPER: susceptibility to water and wind erosion, surface ponding (under cropping), formation of tillage pan, soil color, soil porosity, soil structure, susceptibility to slaking, infiltration rate, and biodiversity status. These indicators were measured in 48 agricultural field-plots to adequately represent the four above-mentioned practices and the different types of geomorphological patterns existing in the area. Additionally, 38 agricultural fields were sampled in the topsoil to assess cultivation practices (tillage, no-tillage) on soil organic carbon, cation exchange capacity, exchangeable potassium, available phosphorous, and soil aggregate stability. Based on the indicators rating methodology, the appropriate statistical tests were applied and the soils under different managements were characterized in terms of their potential quality and their general agricultural value. The obtained data showed that in agricultural areas, significant differences were detected between tillage and no-tillage management practices for the indicators of soil structure and consistency and infiltration rate. In grazing land, significant differences were found for the soil quality indicators of susceptibility to erosion and infiltration rate for the corresponding practices of intensive and extensive grazing. Organic carbon content, exchangeable potassium content and aggregate stability were greatly affected in tillage versus no-tillage management practices.

Mediterranean ecosystems are commonly vulnerable to wildfires. Accelerated erosion processes due to wildfires in those environments constitute a major restrictive factor in their sustainability. This study aims at evaluating the use of the Revised Universal Soil Loss Equation (RUSLE) and the Pan-European Soil Erosion Risk Assessment (PESERA) models in predicting the changes in spatial variability of soil erosion following a wildfire event. A site in Greece on which a wildfire occurred in the summer of 2007 is used as a case study. Soil erosion rates for the site before and after the fire outbreak were estimated by the two models. Inputs for both models included climatic, land-use, soil type, topography, Earth Observation (EO) as well as management and other ancillary data. Both models showed a substantial increase of soil erosion rates in the affected area as a result of the fire, particularly towards the steeper slopes and on areas of high burning severity. Yet, there were noticeable differences in the predictions between the 2 models in terms of absolute estimates of soil erosion rates before and after the fire event. Mean pre-fire erosion rates from RUSLE were ~ 2.5 times higher than those from PESERA. RUSLE predicted considerably higher mean erosion in comparison to PESERA for the post-fire conditions, yet of much less spatial variability. Average post-fire soil loss value, compared to pre-fire, was about nine and six times greater when using the RUSLE and the PESERA model respectively. RUSLE predictions were most sensitive to topographic and rainfall erosivity factors. PESERA showed high sensitivity to the vegetation coverage as well as to the soil characteristics inserted as crusting and erodibility variables. To our knowledge, this is the first study performing an intercomparison of soil erosion rate predictions between these two models, particularly so in the context of the influence of wildfire events. This study provides a key contribution towards our ability to better understand the effect of fire on soil erosion in the Mediterranean and elsewhere, as well as the ability of those widely used models as efficient tools to be used for this purpose. The latter is of key significance and practical value for research and policy decision making purposes alike, where information on spatiotemporal estimates of soil erosion rates may be required.

Soil degradation and desertification processes in the Mediterranean basin reflect the interplay between environmental and socioeconomic drivers. An approach to evaluate comparatively the multiple relationships between biophysical variables and socioeconomic factors is illustrated in the present study using the data collected from 586 field sites located in five Mediterranean areas (Spain, Greece, Turkey, Tunisia and Morocco). A total of 47 variables were chosen to illustrate land-use, farm characteristics, population pressure, tourism development, rainfall regime, water availability, soil properties and vegetation cover, among others. A data mining approach incorporating non-parametric inference, principal component analysis and hierarchical clustering was developed to identify candidate syndromes of soil degradation and desertification risk. While field sites in the same study area showed a substantial similarity, the multivariate relationship among variables diverged among study areas. Data mining techniques proved to be a practical tool to identify spatial determinants of soil degradation and desertification risk. Our findings identify the contrasting spatial patterns for biophysical and socioeconomic variables, in turn associated with different responses to land degradation.

The need for reliable estimates of soil loss under different land management practices (LMPs) is becoming imperative in the Mediterranean basin to inform decisions on more effective strategies for land management. The effect of LMPs on soil erosion and land degradation has been investigated using experiments from November 2008 to November 2011 in an olive grove in central Crete (Greece). The study area was on sloping land with soils formed on marl deposits which are vulnerable to desertification because of surface runoff and tillage. The experimental design included three treatments with two replicates (3 × 5 m experimental plots) corresponding to the following LMPs: (i) no tillage–no herbicide application, (ii) no tillage–herbicide application and (iii) ploughing to 20 cm perpendicular to the contours. The following variables were monitored: surface water runoff, sediment loss, soil temperature at 10 cm, soil moisture content at depths of 20 and 50 cm, as well as selected climatic variables. The results show that the no tillage–no herbicide management practice gave the lowest sediment loss (1.44–4.78 g/m2/yr), the lowest water runoff (1.8–11.5 mm/yr), the greatest amount of water stored in the soil, the lowest soil temperature and the lowest desertification risk compared with the other treatments. Tillage resulted in the greatest sediment loss (13.6–39.2 g/m2/yr) and surface runoff (16.5–65.0 mm/yr), and an intermediate amount of water stored in the soil. In addition, this treatment led to the loss of soil thickness of 3.7 mm/yr because of ploughing. The results demonstrate the high risk of desertification in the investigated region and the methodology can be used in other Mediterranean areas as an assessment framework for evaluating land degradation and the impact of land management on soil erosion.

This study investigates the relationship between fine resolution, local-scale biophysical and socioeconomic contexts within which land degradation occurs, and the human responses to it. The research draws on experimental data collected under different territorial and socioeconomic conditions at 586 field sites in five Mediterranean countries (Spain, Greece, Turkey, Tunisia and Morocco). We assess the level of desertification risk under various land management practices (terracing, grazing control, prevention of wildland fires, soil erosion control measures, soil water conservation measures, sustainable farming practices, land protection measures and financial subsidies) taken as possible responses to land degradation. A data mining approach, incorporating principal component analysis, non-parametric correlations, multiple regression and canonical analysis, was developed to identify the spatial relationship between land management conditions, the socioeconomic and environmental context (described using 40 biophysical and socioeconomic indicators) and desertification risk. Our analysis identified a number of distinct relationships between the level of desertification experienced and the underlying socioeconomic context, suggesting that the effectiveness of responses to land degradation is strictly dependent on the local biophysical and socioeconomic context. Assessing the latent relationship between land management practices and the biophysical/socioeconomic attributes characterizing areas exposed to different levels of desertification risk proved to be an indirect measure of the effectiveness of field actions contrasting land degradation.

Producción Científica, Rainfall is the key factor to understand soil erosion processes, mechanisms, and rates. Most research was conducted to determine rainfall characteristics and their relationship with soil erosion (erosivity) but there is little information about how atmospheric patterns control soil losses, and this is important to enable sustainable environmental planning and risk prevention. We investigated the temporal and spatial variability of the relationships of rainfall, runoff, and sediment yield with atmospheric patterns (weather types, WTs) in the western Mediterranean basin. For this purpose, we analyzed a large database of rainfall events collected between 1985 and 2015 in 46 experimental plots and catchments with the aim to: (i) evaluate seasonal differences in the contribution of rainfall, runoff, and sediment yield produced by the WTs; and (ii) to analyze the seasonal efficiency of the different WTs (relation frequency and magnitude) related to rainfall, runoff, and sediment yield. The results indicate two different temporal patterns: the first weather type exhibits (during the cold period: autumn and winter) westerly flows that produce the highest rainfall, runoff, and sediment yield values throughout the territory; the second weather type exhibits easterly flows that predominate during the warm period (spring and summer) and it is located on the Mediterranean coast of the Iberian Peninsula. However, the cyclonic situations present high frequency throughout the whole year with a large influence extended around the western Mediterranean basin. Contrary, the anticyclonic situations, despite of its high frequency, do not contribute significantly to the total rainfall, runoff, and sediment (showing the lowest efficiency) because of atmospheric stability that currently characterize this atmospheric pattern. Our approach helps to better understand the relationship of WTs on the seasonal and spatial variability of rainfall, runoff and sediment yield with a regional scale based on the large dataset and number of soil erosion experimental stations., Ministerio de Economía y Competitividad - FEDER (CGL2014 52135-C3-3-R; ESP2017-89463-C3-3-R; CGL2014-59946-R; CGL2015-65569-R; CGL2015-64284- C2-2-R; CGL2015-64284-C2-1-R; CGL2016-78075-P; GL2008-02879/BTE; LEDDRA 243857; RECARE-FP7; CGL2017-83866-C3-1-R y PCIN-2017- 061/AEI), Ministerio de Economía y Competitividad (FJCI-2017-33652), Organización para la Cooperación y el Desarrollo Económicos (TAD/CRP JA00088807), Junta de Castilla y León - FEDER (CLU-2018-04)